1. Field of the Invention
This invention relates to a novel crystalline silicate and a process for the production of the same, and further relates to a process for the production of hydrocarbons using this crystalline silicate. More particularly, it is concerned with a process for producing hydrocarbons such as aromatic hydrocarbons from alcohols, ethers or synthesis gas using the crystalline silicate as a catalyst.
2. Description of the Prior Art
The surroundings of petroleum playing the leading part of energy at present are very unstable and it has been feared that a "valley" of energy will come in the last half of 1980s to the 1990s due to deficiency of petroleum. To this end, it is required to practice economy in the consumption of petroleum in future and to use an alternative energy for petroleum such as coal, nuclear fuel, natural gas, etc. In particular, it has lately been watched with keen interest to develop the technique of C.sub. 1-chemistry to make up for the short supply of gasoline, kerosene and gas oil which demands will relatively be expanded by producing them from other carbon sources than petroleum, e.g. coal and natural gas which can be found in abundance in the world.
Methods of producing hydrocarbons from coal can be classified mainly into two methods, i.e. direct method by liquefaction of coal and indirect method through the synthesis gas, and a number of studies have hitherto been made as to these two methods. The liquefaction of coal is generally carried out by subjecting coal to hydrogenation under a high pressure in the presence of a solvent to obtain gaseous or liquid hydrocarbons, but this method is still under development and unfavourable economically and the quality of the products is inferior to petroleum at present. On the other hand, the indirect method, which has already been put to practical use by SASOL in South Africa, consists in a method of converting a carbon source into hydrocarbons by preparing carbon monoxide and hydrogen in the presence of air, oxygen or steam and reacting them in the presence of a Fischer-Tropsch catalyst.
However, the use of the prior art Fischer-Tropsch catalyst such as fused iron or precipitated iron results in reaction products of hydrocarbons including paraffins and olefins, distributed widely from methane to wax and reaction products of various oxygen-containing compounds including alcohols, ethers, etc., and thus it is impossible to obtain selectively valuable products with a specified boiling point range. That is, the yield of the most valuable gasoline fraction is not sufficient and the gasoline fraction cannot be used as motor gasoline as such and should be modified, for example, by catalytic reforming, since it contains little aromatic hydrocarbons or highly branched paraffins or olefins and has low octane number.
The synthesis gas obtained from raw materials such as coal and natural gas can be converted into methanol in known manner, but methanol, as it is, has been used as only a raw material for chemicals at present, which use is considerably limited. Of late, however, a process for the synthesis of gasoline from methanol has been proposed by Mobil Oil Co. as disclosed in U.S. Pat. Nos. 3,894,103-3,894,107. The feature of this process consists in using zeolites of ZSM-5 series with an SiO.sub.2 /Al.sub.2 O.sub.3 ratio of at least 12, different from the prior art zeolites, but in the case of using this catalyst, there arises a problem that several % or more of durene (1,2,4,5-tetramethylbenzene, mp 79.degree. C.), causing plugging of a carburetor of engine, is formed as a byproduct and the catalyst is contaminated with carbon deposited so that its life is short. Furthermore, another process for the direct synthesis of gasoline from the synthesis gas using a mixed catalyst of the zeolite of ZSM-5 series and Fischer-Tropsch catalyst or methanol synthesis catalyst has been proposed by Mobil Oil Co. as disclosed in U.S. Pat. Nos. 4,096,163 and 4,157,338, but this process has also a drawback that a large quantity of carbon is deposited on the catalyst to shorten the life thereof.